Intellectual property boutiques Fish & Richardson; Finnegan, Henderson, Farabow, Garrett & Dunner; and Sterne Kessler Goldstein & Fox maintain dominant positions in America Invents Act litigation, but global Am Law 50 firms continue making inroads at the PTAB.

That's one of the takeaways from Lex Machina's annual review of AIA litigation at the Patent Trial and Appeal Board. Lex Machina's data also show that Apple Inc. and Samsung Corp. remain the most frequent petitioners, but pharmaceutical companies are starting to crack the top 10 on both the petitioner and patent owner side.

“Fish and Finnegan really have a lock on this in a lot of ways,” said Lex Machina legal data scientist Brian Howard. Fish & Richardson filed 123 petitions last year, nearly twice as many as any other law firm, while Sterne Kessler checked in at fourth with 63 petitions and Finnegan at seventh with 52.